Interpretive Summary: The cereal leaf beetle, Oulema melanopus L., (Coleoptera: Chrysomelidae), is a serious pest of wheat, oats, and barley. Originally from Europe and Asia, the beetle was first found in the United States in southwestern Michigan in 1962 and slowly expanded its range to include most states east of the Mississippi River. Recently, damaging populations have been reported in the Middle Atlantic States and some Western States. Current control efforts are focused primarily on the introduction of imported natural enemies. Pest control efforts could benefit from an attractant for cereal leaf beetles for detection and monitoring of new pest infestations. However, basic pheromone (species-specific attractant) knowledge is relatively lacking for Chrysomelidae and the chemical communication of the cereal leaf beetle was unstudied. This study was designed to detect and identify possible semiochemicals used in the chemical communication of the cereal leaf beetle, and a likely pheromone candidate was isolated, identified, and synthesized.

Technical Abstract:
Comparisons of volatiles collections from male and female, Oulema melanopus, feeding on host foliage (oats), revealed an electrophysiologically active male-specific compound, (E)-8-hydroxy-6-methyl-6-octen-3-one (7), that is a new natural product. The structure of 7 was elucidated by spectroscopic and micro chemical studies, and confirmed by chemical synthesis. Antennal electrophysiology showed the sensitive detection of 7 by both sexes, which is consistent with a male-produced aggregation pheromone.